The Ministry of Defence (MoD) published plans for the new Type 26 Global Combat Ship, saying the constructions of the 5,400 ton vessels will help sustain thousands of jobs in the shipbuilding industry.

But the contracts for the 13 warships will not be awarded until 2015 at the earliest, the year after the independence referendum is expected to take place.

Successive defence secretaries, including Philip Hammond, have made clear that only UK firms will be considered for such contracts and have pointed out no British warship has been built by a foreign yard for more than 50 years.

Trade unionists at shipyards on the Clyde have warned that without UK defence contracts the industry in Scotland “would be greatly reduced or, in fact, finished.”

The MoD yesterday confirmed that although the budget for the vessels will not be finalised until the middle of the decade, the contracts for their construction will be worth billions of pounds.